Grinding machine



' Nov. 30, 1943.

R. PRICE ETAL GRINDING MACHINE Filed Feb. 28, 1940 '12 Sheets-Sheet 2 RALPH :JR/c:

- Hanau: :.BALsmL-R Bu mlLauRN A.HoLLsNGR:N

1 2 Sheets-Sheet 6 Nov. 30, 1943. R. E. PRICE ETAL GRINDING MACHINE Filed Feb. ze, 1940 www I* m v l'srmentor attorney RALPH E. PRICE HAROLD E. BALS/GER 23g M/LBURN A. HOLLENGREEN Nov. 30, 1943. RE. PRICE ETAL 2,335,356

GRINDING MACHINE Filed Feb. l 28, 1940 12 Sheets-Sheet 7 zal l zes' Y Snvcnfor LPH e. PR/.cs

RoLn E. .BALslse-R Bu M/LauRN A. HoLLsNsRezN- (Ittorneg l ANov. 30, 1943. R. E. PRICE ETAL 2,335,356

vGRINDING MACHINE Filed Feb. 28, 1940 l2 Sheets-Sheet 8 I- IjIE f f* Y W, '7 7//// A @I4 320 RALPH s. Rice 3Q? Ctto 1111 en Nov. 30, 1943. R. E. #RICE "ET AL. 2,335356 GRINDING MACHINE Filed Feb. 2a, 1940 12 sheets-sheet's #ALPH 'e'. PR/c: maken: z. ALsmrR Pio/BURN A HoLLcNsRse-N Nav. 30, 1943. R. PRICE ETAL v 2,335,355

@BINDING MACHINE 4 Filed Feb. 28, A1940 12 Sheets-Sheet 11 l M "11 "i N O i--J N M "w JN O *N l 36o M i Z l` Lf J. j O l Nov. 30, 1943. R. E. PRICE ETAI. 335,356

GRINDING MACHINE Filed Fab. 2a, 1940 12 sheets-sheen?.

Snucnfor RALPH s. PRIcE HARoLn :.BALslazR m/LRN ,mnognsrlskszw Patented Nov. 30, 1943 UNITED STATES PATENT 'OFFICE A. Hollengreen, Waynesboro, Landis Tool Company,

Pa., assignors to Waynesboro, Pa.

Application February 28, 1940, Serial No. 321,310 16 Claims. v('Cl. 51-95) Our invention relates to grinding machines, particularly of the type known as plain cylindrical grinders, although many of the features hereinafter described are applicable to other types of grinding machines.

It is an object of our invention to provide a machine wherein all the controls are Within easy reach of the operator.

A further object is to provide a single control member with multiple functions.

A further object is to provide means to compensate for variation in temperature of the uid in a hydraulic system whereby to obtain uniform functioning under all temperature conditions.

A further object is to provide an improved coolant system.

A further object is to provide an interlocking relation between the Wheel feed mechanism and the work drive motor.

A further object is to provide an improved feed mechanism.

Figure 1 is a front elevation of our machine.

Figure 2 is a sectional right hand end elevation of the wheel support and feed mechanism.

Figure 3 is a sectional front elevation of the wheel support and feed mechanism.

Figure 4 is a sectional elevation on line 4-4 of Figure 3.

Figure 5 is a sectional elevation of the rapid feed reversing valve and the viscosity compensator. l

Figure 6 is a section thru the timing valve.

Figure '7 is a sectional front elevation of the main control valve.

Figures 8A, B, and C are sectional elevations of pilot valve |90 of Figure 7 in position for normal traverse, dressing and high speed traverse, respectively.

Figure 9 is a vertical section thru the traverse speed control valve.

Figure 10 is a Vertical section thru the traverse plunger cut selector valve.

Figure 11 is a section on the line I I-I I of Figure 10.

Figure 12 is a section thru the tarry valve.

Figure 13 is a section thru the feed control valve.

Figure 13A is a section on the line I3A-I3A of Figure 13.

Figure 14 is a section on the line I-i-III of Figure 13.

Figure 15 is a section thru the valve which determines the traverse speed for dressing.

Figure 16 is a section thru the combined hood and water nozzle.

Figure 17 is a section on the line yI'I--I'I of Figure 16.

Figure 18 is a sectional plan View of the footstock.

Figure 19 is a wiring diagram.

Figure 19A is a wiring diagram of the headstock drive motor circuit.

Figure 20 is a piping diagram.

Numeral I0 indicates the bed of a grinding machine, I I a work carriage slidably mounted thereon, I2 a swivel table mounted for angular'adjustment on said carriage, I3 a headstock, and I4 a footstock, both mounted on said table. A work piece W is rotatably supported on headstock center I5 and footstock center Iii. Any suitable' driving device on the headstock serves to ro'- tate said Work piece. A Water guard I1 prevents coolant from splashing on the operator. Carriage I I may be shifted manually by means of handwheel I8 thru suitable mechanism, not shown. When actuated by power the direction of movement of the carriage is controlled by a reversing lever I9 actuated by dogs 20and 2| on dog rack 22. The rate of traverse is determinedv by the setting of valve 23. For dressing traverser the rate is controlled by valve 24. A wheel base 25 having a grinding wheel 2t rotatably mounted thereon is slidably mounted on the bed I0 for movement toward and from the work carriage. A cover member 27 hinged for easy inspection encloses the wheel base and grinding wheel and has a separate compartment therein for each of said parts. A handwheel 28 provides a manual means for shifting said Wheel support toward.

and from the work. A second cover 29 similar in shape and size to cover 21 encloses the space over the coolant tank.

Footstoclc drawn also by a piston 51 slidably mounted inv a cylindrical bore 58 in said footstock. Said piston may be actuated in one direction by uid under pressure from a valve 59 which is operated by a pedal 69. When so actuated, said piston will engage the iianged portion of -nut 53 and shift said nut and spindle in a direction to withdraw center I to an inoperative position.

Feed mechanism In Figures 2, `3, 4, 5 and 6 are shown the mechanisms both manual and power operated for moving the wheel support toward and away from a work piece. There are in effect four of these mechanisms:` (l)A the manual mechanism actuated by handwheel 28; (2) a rapid feed mechanism; (3) a continuous grinding feed mecha- Y nism; (4) an intermittent grinding feed o-perated during traverse grinding and consisting of a mechanism for actuating the above mentioned continuous feed mechanism intermittently.

The manual means for feeding Wheel 25mcludes a handwheel 23. Said handwheel is connected thru a system of gears to a shaft 45. Said handwheel is rotatably mounted on a bushing 62 on shaft 45. A ring gear 63 is mounted on a flanged portion of handwheel 23. Said ring gear ts on said handwheel tightly enough to rotate therewith unless held against rotation by some means such as locking pin 5t. A secondv ring gear 64 is keyed to shaft 45. A differential' gear consisting of two pinions and 55 is rotatably mounted' in a recess in said handwheel. Said gear is supported on a shaft 51 in said handwheel and parallel to the axis thereof. Pinion 65 meshes with ring gear 63 and pinion 65 with ring gear 64". When handwheel 28 is turned with locking pinv 58 in back position as shown, the drive from handwheel 25 to shaft 4B is direct, with said handwheel, ring gear 33, differential pinions 65' and 65, ring gear 54, and shaft 40` turning asa unit. When ring gear 53 is locked by pin 68, the drive from handwheel 28 to shaft is a 10 to l ratio. As the handwheel 2B and differential pinions and 56 rotate about the handwlieel axis, saidpinions are caused to rotate about their own axis by the engagement of pinionA 55 with ring gear 53. Pinion 56 thus causesrotation of ring gear 64: and shaft 45 at the rate' ofcne revolution to ten revolutions' of handwheel 28. Obviously this ratio of 10 to l may be varied to suit any particular case. With this fine feed arrangement in combination with thev other features of the feed mechanism to be described later, the operator may accurately and easilyeffect any change in size directly by setting the hand4 feed and without measuring a work piece after each of a series of test cuts.

On one end of shaft 40 is a cut a worm (not shown). Said worm. engages a worm gear 42 which is secured to a vertical shaft 43. Both of saidshafts are supported in bearings in the wheel support 25. Said handwheel shaft is mounted on three ball bearings, one of which supports the worm end thereof. On an extension of said shaft beyond the worm portion a finger 35 is rotatably mounted in frictional engagement therewith. Said finger engages a switch 31 for controlling headstock motor 495. At the lowerv endof said shaft 43 is secured another worm gear 44. Said wormv gear engages a worm or feed screw shaft'45 rotatably and slidably supported inthe bed l0. Said screw may be moved rapidly endwise by'piston 46 in cylinder 41, or it may be rotated by rack 55' in contact with pinion 5lon saidscrew shaft, or it may remain stationary while worm'` gear 44 turned by hand-wheel 28 moves relative Athereto carrying with it the wheel support- 25. In either of the'rst two cases the wormigear 44'becomes in effect a nut because it is held against rotation by worm gear 42 and the worm on shaft 40. During the rapid feed, the screw shaft 45, worm gear 44, and wheel support 25, are moved bodily. The backlash between screw 45 and worm gear 44, between worm gear 42 and its worm and the torsional strain in shaft 43 are taken up during the rapid feed movement. When screw shaft 45 is rotated by piston 10 for a grinding feed, gear 44 and wheel support 25 are moved relative thereto'while said screw remains motionless axially. The backlash mechanism described above may be taken up either in response to rotation of screw 45 or to rotation of handwheel 23. At the end of the grinding feed, the feeding movement stops and grinding stops as soon as the wheel sparks out. Piston 46 is adjustably mounted on the threaded end 48 of shaft 45 and is prevented from turning thereon' by a split nut 49 which has a clamping screw 69 extending beyond said nut into an opening 6I in piston 45. In order to eliminate back lash inthefeed mechanism, a lock mechanism is providedto prevent rotation of shaft 43 during the movement of. the wheel support by power. While the design of the feed mechanism does not require a backlash mechanism this one is set forth as an optional construction. Said mechanism. consists of a pair of tubular members 35 and 3l slidably mounted ina bore 32 in wheel base 25 adjacent vertical shaft so that said bore joins the bore thru which said shaft passes. Said tubular members are axiallyk spaced in bore 32 and a portion of the inner end surface of each is shaped to conform to the cylindrical surface of shaft 43. Areduced portion 33 of a shaft 34 passes thru said tubular members. The end of said portion is threaded.

to t the threaded bore of member 35. Shaft 34 extends beyond the wheel base at the left hand side thereof and has mounted thereon a handle 35. Turning said handle results in drawingsaid tubular members together to lock shaft43 against rotation or in separating said members to -release saidshaft.

In addition to rack 53 and pinion 5l the grinding feed mechanism includes a piston 1i) integral with said rack. Said piston is mounted for axial movement in cylinder 1l. The extent of movement of piston 13, and hence the amount of grinding feed, is. determined by the settingof an adjustable positive stop 13 in the head of cylinder 1l; The amount of' adjustment of said stop may be determined by a knob 15 graduated in terms of. wheel movement. A threaded insert 14 in stop 13 enables the operator to set knob 15 accurately. For example, with piston 15 at the. extreme left hand position and knob 'l5V set at Zero, inserty 14 may be adjusted until it en-` gages the" head of piston 15. In this position there would be no grinding feed because piston 1'5 couldnot be returned to a positionfrom which it couldrotate screw shaft 45 to effect such a feed.

The means for supplying fluid under pressure to cylinder 41 consists of a valve S5 in a housing 8|, saidhousing is enclosed at both ends by end plates 82 and 53. Fluid under pressure directed by valve 262 thru line 42| may be applied at the right hand'end of said valve 8! to shift same to direct other fluid under pressure thru lines 84 and 85to^the head end of cylinder 41. Exhaust pressure or a spring 15 may be applied at the- 8S and 81 lead to the rod end thereof. Check valves 88 and 89 permit the passage of fluid under pressure to cylinder 41 thru lines 85 and 81 but the exhaust uid returning thru said lines must pass thru throttle valves .90 and 9|, respectively. Lines S4 and 86, and their corresponding ports in cylinder 41, are located between lines 85 and 81. A piston 45 moves from one end of its stroke to another, the iirst part of the stroke is open to unrestricted exhaust thru one of the lines 84 or 86, but as the piston 46 continues it cuts off this exhaust line and thereafter the only exhaust is thru lines 85 or 81 depending on the direction of movement, and the throttle valve in each of these lines restricts the ilow of exhaust iiuid and thus cushions the stopping of the wheel support.

A line 413 from the head end of cylinder 1| to the left hand end of valve housing 8| permits expulsion of air in said cylinder, thus eliminating the need for bleeder tubes. Bleeder tubes are a disadvantage at slow speeds because the volume of iiuid supplied at such speeds does not exceed the capacity ofthe bleeder sufliciently to maintain the necessary minimum pressure on the rapid feed piston to keep it moving. With our improved arrangement, valve 8|] closes off line 413 during feeding so that full pressure is exerted against piston 10.

Timing mechanism In Figure 6 is disclosed a timing valve for deter'- mining the duration of a plunge cut grinding operation. Said valve consists in the valve member I slidably mounted in a bore ll in cylindrical housing |912, sometimes referred to here-A after as a timer. One end |03 of said Valve is smaller in diameter than the rest of the valve and fits in a bore lfl of corresponding diameter formed in a member |05 inserted in bore IiiI. The portion of said valve which may be acted on by fluid under pressure in lines IIQ and IIS is therefore smaller than the opposite end thereoi. An end plate IE5 has a line Id therein leading to bore I @4. YAnother end plate |98 has a line |539 therein leading to bore Il. On one side of housing |62 are two lines IIS and III located toward the right hand end or" the valve. In the position of valve Iii shown, line III is connected thru peripheral groove I I2 of valve I |30 with a line IES on the opposite side of said housing. On said opposite side but toward the left end of the valve are two additional lines IIi and H5. Said lines are connected by a passage IIS in which is located a ball check valve which permits passage of huid from lines |54 and IIE. Valve IGI? has a closed bore forming a passage Ill' which is connected to the chamber at the left end of bore IGI thru a port IIS. Spaced axially from said port is a second port IIS join-A ing said bore IIJI and passage ||1 thru a peripheral groove |253. Said groove forms a chamber between said valve and said bore IBI. Movement of valve IGI! to the left is retarded by the fluid' exhausting from the bore IBI thru line IIS and' thru a throttle valve I2I in said line. When the valve moves to a point where port II@ coincides with line IM, the fluid may be released thru passage Ill, passage IIB, port IIB in the valve, and exhaust line IIA in the housing, thus permitting the Valve to move quickly to reverse position.

Relief valve In Figure 5 is shown another novel feature of our hydraulic system. This feature is a relief valve which compensates for variation in viscosity so that mechanisms operated by fluid under pressure will function at the same rate regardless of the temperature of the hydraulic medium. Said valve consists of a movable valve member |30 having opposite ends of different diameter, and mounted in a cylinder bore |3| having an internal surface corresponding in shape to said valve member. Said valve member is hollow from end to end and contains a check valve |40 which will permit the passage of fluid from the small end to the large end under certain abnormal conditions. Said valve is connected into the hydraulic system at a point relatively close to the pump |32. The small end |33 of cylinder ISI may be connected directly to the pressure supply line |31 leading from pump |32. The large end iffl of said cylinder may be connected to said supply line thru line |35. A throttle valve |38 for regulating the pressure in the system is placed in line |31 between the points of connection between said supply line and said cylinder. The small end |33 of cylinder I3I is subjected to pressure Which is determined by the setting of valve |38. The pressure at the large end |34 of said cylinder is determined by the resistance to iiow offered by the mechanism or mechanisms to be actuated by the iluid under pressure. As the pressure in the large end of the cylinder approaches that in the small end, said valve member ISB, because of the difference in diameter, will be shifted toward the small end to a position to open exhaust line |39 and relieve any excess pressure in the system.

Traverse mechanism The traverse mechanism on our machine consists of a cylinder E56 secured to bed IB, and a piston I5I slidably mounted in said cylinder with a piston rod |52 protruding from one end and a tail rod |53 protruding from the other end, both of said rods are attached to carriage I I by means of suitable brackets IFAI and |55. The supply of uid under pressure for driving said piston is controlled by a series of valves mounted in a body |60. Said valves include a start and stop or bypass valve Ii slidably mounted in bore |62. Said valve may be actuated to operative position, in this case the leit hand position, by iiuid under pressure from a source to be described later, and in the opposite direction by a spring |63. Cylinder |59 is connected to said valve thru lines |55 and |66. Fluid under pressure for actuating piston |5| is supplied to valve 55| from a pressure actuated reversing valve I1!! thru lines 1| and |12. Valve I1@ is mounted in a bore |13 in the valve body IEE and has reduced portions |14 and |15 at opposite ends thereof. Said reduced portions fit in tubular inserts |15 and |11 at opposite ends of bore |13. Each end of said valve is bored to form connecting passages |18 and |19, connecting spaced radial passages and |8| at one end, and mi2-and HB3 at the other end. In one extreme position of said reversing valve |10, radial passages Iiii and |32 are aligned with exhaust ports leading into exhaust passage |85, and in the other extreme position radial passages IGI and are aligned with said exhaust ports.

Actuating iluid under pressure is supplied to said reversing valve from a pilot valve thru a line ISI. Said pilot valve also directs fluid under pressure alternately thru lines |92 and |93 to shift reversing valve |19 in yone direction or the other. Opposite ends of bore |13 are conopposite ends of bore 28|. A throttle valve 2|4- determines the rate of flow o f iluid in said lines and therefore the rate of movement of valve 200. Said valve receives a supply of fluid under pressure from feed control valve 308 thru line 22|. Said fluid is directedby valve 308 thru either of the lines 222 or 223 depending on the direction of movement of said valve. Said lines join into a single line 224 leading to valve |6|. The volume of uid directed thru said lines depends on the rate of movement of valve 203.

Pilot valve The pilot valve |98 is mounted in a bore 315 in valve body |60. Said valve has two longitudinal passages therein; a long one 315, and a short one 311. Three spaced, radial ports 318, 319 and 333 in valve |90 are joined by passage 315. Three other spaced, radial ports 38|, 382 and 383 in said valve are joined by passage 311. The function of passage 315 and associated ports is to provide escape for exhaust fluid in Various positions of Valve |90. The function of passage 311 and associated ports is to provide a continuous supply of fluid under pressure to hold valve 5| in operative position while valve |93 is reciprocated during a traverse grinding operation. Said valve |90 has three different strokes, a short stroke for normal traverse determined by pin 23| in .panel 230, a longer stroke determined by springs 233 and 234 for dressing, and a still longer stroke for high speed traverse.

The control members for the hydraulic system are mounted in the bed i 3 with knobs or handles for same protruding thru a cover panel 230. In some `cases the movable part of a control member is secured to said panel while the stationary part is solidly mounted in the bed I3.

In Figure 9 is shown the reversing and traverse control member. This member consists of astationary tubular part 235 held securely in the bed |0 by means of a screw 233. A core member -231 is rotatably mounted in said tubular part 235 and extends thru said panel 230. A flanged portion ,238 at one end of said member bears against a faced off portion of said panel and is held in that position by a collar 233 on said `core inside said panel. Said collar is secured to said'core by means of a screw 240. Pivotally attached to said flanged member is the lever i3. Said lever is bored to receive a spring pressed plunger 242 which bears against a cam surface 243 on flange 238 to hold said lever in position so that alug 244 there-on will be in the path of dogs 20 and 2 I. A pin 23| on said panel extends into an elongated recess 232 in lever I3 to limit the movement thereof during normal traverse. When it is desired to permit carriage movement beyond the limits set by said dogs, said lever may be pulled baci; against the action of said spring pressed plunger 242 in which position the lug `2M will be out of the path of said dogs. In this position alsopin 23| will have no effect on lever 3. However, leaf springs 233 and 234 secured to ythe end plates of valve |83 and extending into thepath o fvalve |90l mark thelimit of movement of said valve during a dressing operation. For a rapid traverse movement said valve is shifted still farther against the springs 233 and 235. At the end of said core member 231 inside the bed is mounted an arm 245 which extends downwardly to engage pilot valve |39. Said core member 231 is bored to receive a throttle valve 235 which controls the flow of fluid between spaced radial passages 241 and 248. Said throttle valve may be adjusted by a knob 249 which is threaded into core 231. Passage 241 is aligned with an exhaust passage 259 in the tubular part 235. A check valve 25| in said passage maintains a slight back pressure on the exhaust system. Passage 248 is aligned with an inlet passage 252 which in turn is connected to the exhaust port of pilot valve |90. Said valve is grooved circumferentially at each of said radial passages so that iluid may pass thru said core regardless of its angular position.

Traverse and plunge cut selector Figure l0 discloses a valve the function of which is to prevent traverse movement of the work carriage during a plunge cut grinding operation. Said valve consists of a stationary tubular member 233 inserted in the bed l0 and held in place by a screw 25|. A valve member 2'32 is rotatably mounted in panel 233 for insertion in said tubular member. Said valve is held in proper axial position by a flanged portion 253 thereon which bears against a pad 234 on panel 230. Said pad is faced on both side-s. rIhe ange bears against the outside while a collar 255 held in place by a screw 283 bears against the inside of said pad. A knob 26'! on said valve provides means for shifting said valve from one position to another. Member 230 has two radial passages 268 and 2559 in the upper portion thereof. Said passages are connected by a short passage 210. Fluid under pressure may be introduced thru port 21|. The lower portion of member 280 has two spaced radial passages 258' and 269' which are in effect continuations of passages 260 and 269. Fluid under pressure is conducted from passage 238 thru port 212 to actuate valve 80. Another radial passage 213 in member 250 in the same plane as passages 239 and 238 join a longitudinal passage Y214 therein which directs fluid under pressure to the traverse mechanism. A longitudinal passage 215 joining radial passage 269' directs fluid back to the reservoir. Valve 262 has two spaced peripheral grooves 218 and 211 in alignment with passages 289 and 259. Groove 216 is continuous and permits passage of fluid as long as fluid enters port 21| Groove 211 is broken by a plug 218 which prevents passage offlui-d in some angular positions, for instance, in the position shown in Figure l1. In this position the pressure of the fluid in passage 289 exerts such a force that it binds valve member 232 and prevents or makes dificult the turning of said valve while the uid is directed thru passage 238 to move the wheel to and hold it in grinding position.

Taffy The tarry valve is disclosed in Figure 12, and is of the same general construction as previously described valves in that it consists of a stationary tubular member ist inserted in the bedje and held in place by means of .a screw 238. A longitudinal passage 23| in member |35 joins a radial passage 232, and another longitudinal passage 283 joinsa radial passage 23,11. A coremember 285 has a pair of spaced peripheral grooves 286 and 281 in each of which are radial passages 288 and 289 respectively. Passages 238 and 289 are joined by a longitudinal passage 200 in which is inserted a tarry valve 29|. Fluid from the reversing valve bore |13 passes thru lines |34 and |05 and said valve in both directions. Said core is threaded into tubular member and is therefore not rotatable as in some of the other valves. Valve 29| may be adjusted axially by means of a knob 252 which is threaded for this purpose in core 235.

Feed control came In Figure 13 is disclosed the valve for controlling the feed mechanism and which is effective also to start the grinding operation. Said valve like previously described valves consists of a short tubular member 220 inserted in the bed I0 and secured therein by means of a screw In the upper part of said member 220 is a longitudinal passage 302 joining a radial passage 303. In the lower part of member 220 are a pair of spaced radial passages 304 and 305. A longitudinal port 306 connects with passage 304, and a longitudinal exhaust passage 302| connects with passage 305. Groove 3|0 in valve 366 is not continuous by reason of a pin 332 therein. The angular position of said pin and hence that of valve 30B determines whether iiuid shall be directed to the traverse selector valve 262 or to the exhaust passages 305 and 301. Valve 368 has spaced peripheral grooves 300 and 3|6 in alignment with the radial passages in tubular member 226. A radial passage 3|| in groove 3|0 extends part way thru said valve 300. A radial passage 3|2 in groove 309 extends all the way thru said Valve and at right angles to the passage in groove 3|0. A longitudinal passage 3|3 connects said radial passages. A throttle valve 3|4 may be adjusted by means of a knob 3|5 threaded in said valve 308 to regulate the flow of fluid between said radial passages 3| 0 and 3| 2. Said fluid passes from passage 3|2 thru port 306 and line 22| to feed cylinder 10. Valve 308 has a flanged end 320 which bears against a pad 32| on panel 230. Said pad is faced on both sides. A collar 322 held in place on said valve by a set screw 323 bears against the other side of said pad. A lever 324 for rotating said valve 363 is formed integral with said flange. Another radial passage 330 is formed in said tubular member in the same plane as passages 303 and 305 and at right angles thereto. Said passage 330 joins a longitudinal passage 33| which directs fluid thru line 420 to the traverse plunge cut selector valve 252.

Dresser control telve Figure 15 discloses a valve for controlling the traverse speed during a dressing operation. This valve consists of a stationary tubular member 340 held in position in bed I0 by means of a screw 34|. In the upper part of member 340 is a longitudinal passage 342 joining a radial passage 343. In the lower part of said member is a longitudinal passage 344 joining a radial passage 345. A check Valve 346 in said radial passage 345 permits a iiow of iiuid to passage 344 which is an exhaust passage. Avalve 341 threaded internember 340 has two spaced peripheral grooves 348 and 349 thru which are drilled radial passages 350 and 35| respectively. A longitudinal passage 352 joins said radial passages 350 and 35|. A throttle Valve 353 in passage 352 may be adjusted axially by means of a knob 354 threaded into saidvalvel 341.

Coolant system The coolant system may consist of any suitable coolant pump driven by a, motor 360. Coolant fluid from said pump may be introduced in any suitable manner into a passage 36| in cover 21. The front end of the Wheel guard portion of said cover is recessed to receive a combination hood and nozzle 362 which is pivotally secured therein by a Pin 363. The portion of said pin passing thru said hood has a at surface 364. The hole in said hood thru which said pin passes opens at one side to a nozzle formed by the upper wall of said hood and a web portion 365. Pin 363 thus serves as a shut-off valve. A screw 366 passes thru the side of said hood and thru a slot 361 in cover 21. Said slot permits said hood to be adjusted to correspond to the size of the wheel.

Operation Starting the machine is effected by start switch 400 which completes a circuit from LI thru stop switch 40| to relay and L3. Energizing relay starts the wheel motor 402, the hydraulic pump motor 403, and generator motor 404. Another contact 405 on said relay provides a holding circuit around switch 400. j

To place a work piece in the machine the operator depresses pedal 60 to shift valvey59 and direct uid under pressure to Withdraw footstock center I5. Fluid under pressure is supplied to said valve from control valve 303 when lever 324 thereof is in inoperative position. When said lever is in operative position, the line 225 is opened to exhaust thru valve 308. This provides a safety feature in that fluid under pressure cannot be supplied to withdraw said footstock center to release the work while the other parts are operating.

The operator then moves lever 324 to the right to shift valve 308 in tubular member 220, releasing the pressure in line 225 and permitting a. flow of fluid under pressure from line |31 thru passage 302 in groove 3|0, and passages 330 and 33| and line 420 to selector valve 262 and thru line' 42| to feed timer Valve |02 and rapid feed control Valve 80. Said fluid is also directed by passage 3| thru throttle valve 3|4 passages 3|2 and 304 to port 306, from which it passes thru line 22| to actuate the grinding feed either continuously or intermittently, all of which will be described later. i

Fluid under pressure directed by valve 262 thru line 42| passes first thru a hydraulic timer |02. Part of said fluid passes from line 42| thru line |09 to shift the valve member |00 from right to left. Another part of said fluid passes from said line 42| thru line and peripheral groove H2 of valve |00 thru line 3 to shift feed valve 80 to operative position and hold it therefor a predetermined time. Movement of valve |00 from right to left is controlled by the uid being forced out thru line |5 and thru throttle valve |2| into line ||4. When valve |00 opens line ||4 thru peripheral groove |20, passage ||1, and ports ||8 and ||9 to bore 10| further movement is uncontrolled. Line is blocked by valve |00 and line |3 is connected by peripheral groove ||2 of valve 00 to line |0 which allows valve 80 byl spring 16 to be Vreturned to its original position. Valve |00 may be reset by fluid under pressure in line ||4 thru valve |22 and line 5 to the left end of housing |02 When the pressure at the other end of said cylinder is released byshifting lever thehead end of rapid feed cylinder 41.

"tactor'3- At the ,gized to 'start coolant motor 1366. Said contactor 'has two normally vopen circuits and a closed Vfor said generator. circuits-is `in the line between `the exciter and further axially but the `rotating 'line480 to said valve which directs it to line 84 and thru check valve 88 therein and line 85 to Said fluidalso actuates a pressure switch 485 to start the work drive motor 499 completing a circuit ii 31 selector switch '495 to consame time, contactor 2 is enerthru' limit switch circuit. The work drive motor is of thetype disclosed .in copending application, Serial No.

238,657, Vfiled November`3,'1938, and includes the motor490, a generator 49| for supplying current to said motor, a rheostat 492 for varying the voltage on the generator eld and an exciter 493 One of said normally open the generator, the other between the generator andthe motor. The normallyrclose/d circuit is yin the -motor armature circuit and provides Ya dynamic brake for motori490 when contactor 3 is deenergized. The motor `circuit does not form a part of the present invention except for the method of starting, and will be furtherreferred to only insofar 'as the starting device Vis concerned. Piston 46 in cylinder 41 and wheel support 25 are movedrapidly-to position the grinding wheel 26 close to the surface of the piece to be ground. Fluid is discharged from cylinder 41 thru lines 86 and -that piston 46 moves at top speed. After ypiston -46 has closed line 86 said fluid can exhaust only thru line 81, and throttle valve 9| therein checks the speed of piston 46 and provides a cushioned `movement against a positive stop. .Afterpassing 'thru-valve 9| exhaust fluid enters Aline 86 Vfrom which .it passes thru valve 80 to exhaust. passage 513917. On the withdrawal movement, throttle -valve 90 in line 85 effects the cushioning. The rapid v.feed movement is limitediby screw 45em- .gaging a stop 1 1.

Assuming .that the grinding .operationis a plunge cut, fluid under pressurein line 22| Venters chamber y455 of valve lfl rand :is .directed thru Vpassage 4H), valve410, and line 1412 to the .head Aendofrcylinder 1|.

Piston 10 Ainsaid cylinder moves rack 50 in mesh with pinion 5| on :feed screw 45. Saidscrew rotates in mesh with Yworm `gear44 on `the end .of .vertical shaft 143. Said screwbeing against a positive stop can move no movement lserves to insure a good bearing against said stop. This is true'also of the engagement between screw 45 and gear 44. Shaft 43 and gear 44 are held against rotation by worm gear 42 at the other end of the shaft in mesh with a yworm '.(not shown) on shaft 49 of handwheel 28. Thus gear 44 and with it the entire wheel support assembly must move relative to screw 45 in response to rotation thereof. When valve 89 is shifted from left to right as previously described in connection with the operation of the rapid feed, fluid under pressure in line '86 which effects withdrawal of the rapid feed mechanism also enters'the rod end of cylinder 1| to reset piston 19 and the grinding feed mechanism. rThsreset lis always a continuous movement and is independent of the Worktraverselmovement. Valve 80 also opens an yadditional-exhaust from the head end of cylinderlll thru lines 412 and 413 thru said 4valve 81. Line 86 is unrestricted so fro Line 41.3 also serves as a bleeder line to permit the escape of air from cylinder 1|. Thisiline-is 'blocked by valve 86 `during the feed movement.

In order to control the amount of stock removed during-a grinding cycle,ithe strokeV length of piston 19 and hence of thegrinding'feed 4may be adjustably limited by stop screw 13. The exact amount may be set by graduated knob`15.

To reset the feed mechanism for a change in size the operator uses the Ygraduations on the handwheel 28 by which he makes a direct setting from one size to another. For example, if it is desired to increase or'decrease a given size by .010 the change will'be counted out onthe graduations and the position of the wheel surface will be shifted .010. Thereafter, for each grinding operation the wheel will move in to the same position and once it has sparked out, it will grind no further.

Lost motion in the feed mechanism exists between worm gear 44 and screw 45, between worm gear 42 and its worm (not shown) and the torsional strain in Vertical shaft 43. This lost motion is the same for every feed movement and turning handwheel 28 merely changes the position of the grinding wheel at which the lost motion is all taken up. This is true regardless of the direction of movement of the handwheel or the position of the wheel base. This lost motion is all taken up during the rapid feed movement before the grinding feed begins. Any adjustment of the feed by handwheel 28 takes said lost motion into account and the change in size is that indicated by the movement of the handwheel. The rapid feed movement vends when screw 45 engages a positive stop 11 so that when said screw is rotated for a grinding feed it cannot move axially relative to worm gear 44 before said gear begins to move carrying the wheel support with it. Since all lost motion is taken up Vsaid gear cannot rotate in response to rotation of said screw. Therefore, it becomes in effect a nut and moves bodily along with the wheel base and `|50 is lconnected thru chamber 439 of valve ISI f with line |12. Line |65 leading to the other end of cylinder |50 will be connected thru chamber 432 of valve 16| with line |1I. Fluid under pressure for'shifting piston |51 in'cylinder |50 and hence for traversing carriage is conducted from pressure line |31 thru line 435 to chamber 436 in valve |90. Said chamber is in constant connection with line V|9l leading to reversing valve |19. However, as said Vvalve is-actuated either by hand or -by dogs 29 or l2|I on carriage Il, said chamber and the fluid supply passing therethru are connected alternately with ,lines |92 and |93. lFluid under pressure in -said -lines is directed alternately'to opposite ends of valves |10 and 260 to effect reciprocatingmovements thereof. When said fluid acts on the'small portion |14 of valve |19, said valve moves rapidly to the right until itcovers the Y-port leading to exhaust line |86. The fluid Which-isithus `trapped between the yend of the `valve and insertffl-il must pass thru line |95, tarry valve29l, fand-linefM to the corresponding chamber at the other end of the valve. The setting of valve 29| determines the rate of flow and hence the speed of movement of the valve during this period. The slower the valve travels the longer the dwell period.

As said valve covers the port leading to exhaust line |86, the land portion 440 of valve |10 covers line |9| and at the same time the end portions of the valve cover the ports leading to exhaust line |86. In this way the traverse movement of the carriage is stopped positively and accurately. Said valve continues to move toward the right at a. rate determined by the setting of valve 29| until the radial passages therein come in line with the port leading to exhaust line |86. The entrapped fluid may then escape thru radial passages |80, axial passage |18 and passage |8| to exhaust line |86, thus permitting valve |10 to move rapidly to reverse position. Valve |10 has thus been shifted to a position where fluid under pressure from line |9| is directed by said valve thru line |1| and chamber 432 of valve |6| to line |65 leading to the right hand end of cylinder |50, thus causing piston |5| and carriage to move to the left. Exhaust iiuid froml the other end of the cylinder is carried thru line |66, chamber 430 of valve |6| and line |12 to Valve |10 where it is directed into exhaust line 445. Said line is divided into two branches 446 and 441. Line 446 leads to the dresser control valve 341 shown in Figure 15. Line 441 leads to a chamber 448 in valve |90 and from there thru a line 252 and thru the throttle valve portion 246 of core 231. The rate of traverse is determined by the setting of said throttle valve 246 which is adjusted manually by means of knob 249. The normal stroke of valve 90 is so short that chamber 448 is always in position to direct fluid from line 441 to line 252. When selector knob 261 of valve 262 is shifted to change from the plunge cut to the traverse cycle, pressure on valve |6| is relieved and said valve is shifted by spring |63 to the right to connect lines 22| and 4|0. Fluid is thus directed thru valve 410 and line 412 to cylinder 1| to effect a continuous movement of feed piston 10.

At the same time the reversing valve |10 is shifted, fluid under pressure is directed thru the same line |02 to shift automatic feed valve 200. Said fluid acts on a reduced portion 203 of said feed valve in the bore of tubular insert 2| The fluid trapped between the one end of said feed valve and the insert is discharged thru a line 2|2 to the corresponding space at the opposite end of said valve. A throttle valve 2|4 in said lines 2|2 and 2|3 determines the rate of flow of fluid and hence the rate of movement of said valve 200. Said throttle valve as a rule need be adjusted only when the set-up of the machine is changed. Fluid under pressure is supplied to said valve 200 from Valve 308 thru lines 22| and 450. Throttle valve 3|4 which is a part of valve 308 determines the volume of uid passing thru valve 200. Said feed valve moves rapidly to a position to connect line 450 with line 223. Fluid then passes thru line 224 chamber 455 in valve |6| and line 4|0 to feed cylinder 1|. Said flow continues as long as lines 450 and 223 are in communication. This period is determined by the rate of move.- ment of the valve which is in turn determined by the setting of valve 2|4. At the end of this period the entrapped fluid in the space at the end of the valve is released thru passages 204, 205 and 208 in said valve, said passage 205 having connected with exhausty line 456.

Valve 200 thereupon moves rapidly to the end of its stroke. The fluid which passes thru said valve during the openportion of the stroke causes an incremental movement of the slow feed piston 10. The magnitude of each increment is determined by the length of time during which fluid passes thru said valve, and the velocity of the fluid. The velocity is determined by the setting of valve 3|4 (Figure 13). Thus at each reversal of the carriage an automatic feed valve is actuated simultaneously with the reversing valve to effect a feeding movement of the grinding wheel toward the work.

In the operation of valve there are three different ranges of movement; a short movement for normal traverse, a longer movement for dressing, and a still longer movement for rapid traverse. Figures 8A, B, and C shows said valve in the left hand position for each range of movement; A, normal; B, dressing; and C, rapid traverse.

During normal traverse, as illustrated in Figure 8A, valve |90 has a very short movement which is limited by pin 23| in recess 232. Fluid under pressure from line 435 is directed alternately thru chamber 436 to lines |92 and |93 to shiftJ the reversing valve |10 and the automatic feed valve 200. At thesame time fluid from line 425 and selector valve 262 passes thru chamloer 426 in valve |90 and then thru line 421 to actuate bypass valve |6| and position it for traverse operation. Exhaust fluid from cylinder |50 is directed by valve |10 into line 445 from which it passes thru line 446 to dressing control valve 341 and thru line 441 and chamber 448 of valve |90 and line 252 to traverse control valve 246. The minimum traverse speed is obtained with dresser valve `341 closed entirely and with valve 246 at its smallest opening. The maximum traverse speed is obtained with both valves wide open.

During dressing traverse lever |9 is shifted toward the operator so as to remove pin 23| to clear dogs 20 and 2|. The stroke of the valve is increased as shown in Figure 8B, but is limited by the springs 233 and 234. Exhaust fluid may not escape thru line 441 and valve 246 because chamber 448 in said valve is out of alignment with the ports for lines 441 and 252. Exhaust fluid, therefore, must pass out thru line 446 and valve 341 in which a throttle valve is set to permit a carriage traverse speed suitable for dressing a grinding wheel. In this position of valve |90, chamber 42S has moved out of line with the ports to lines 425 and 421 so that fluid cannot pass from one of said lines to the other. However, fluid under pressure from line 435 may pass thru chamber 436 and port 38| topassage 311 from which it may pass thru either of the ports 382 or 383 to line 421 to hold valve |6| in operative position depending upon whether valve |90 is in its left or right hand position.

In the position of valve |90 shown in Figure 8C, said valve has been moved far enough to distort springs 233 or 234. Merely releasing lever I9 will permit said springs to return said valve to dressing speed position. Ports 382 and 383 remain in register with the port leading to line 421. The chamber 436 which directs fluid under pressure from line 435 to either of lines |92 or |93 to actuate the reversing and feed Valves |10 and 200 respectively is shown out of register with fluid supply line 435. However, said chamber and said lines are in register long enough, as the valve moves from one position to the other, to permitthe passage of fluid under pressure .to actuate 'Valves HS and 236i. Exhaust fluid in line M1-may escape thru chamber iii-2l, port lii, passage 316, port sli), and chamber @l to exhaustline 188.

'In the opposite position of valve Eil@ said exhaust may pass .directly from line Aldi to chamber 146| and exhaust line i865. Exhaust thru these lines is unrestricted so that the carriage will move at maximum speed.

In order to have a continuous or plunge cut yfeed and at the same ime a short reciprocating movement of the carriage, a bypass valve Y41!) is so positioned that it may direct fluid under'pressure to the cylinder H either from valve IGI or from line 22! thru bypass passage @1L If it is desired. to cut out the traverse movement, valve 252 is turned to plunge cut position vas shown in Figure 19. The supply of fluid to passages 213 and 2li! is cut olf and hence no fluid under pressure is directed thru line 6125, chamber 426, and line @El to shift valve It! to a position `to permit iiuid under pressure from reversing valve il@ to be directed to carriage traverse cylinder and the traverse mechanism remains inoperative.

The output of the pump passes through line 31 and throttle valve E33. Said throttle valve is set to create a back pressure suitable for ma- -chine operation, and is imposed upon the smaller area of valve i3d. In chamber X the pressure .caused by resistance of machine operation is imposed upon thelarger area of valve i3@ in chamber Y. When the pressure caused by machine Vresistance equals the back pressure caused by the resistance of the throttle valve 133, valve I3!) shifts to the right due to large area at the vmachine resistance end of said valve and oil `escapes into exhaust line Z thus maintaining a ments between said supports, mechanism for controlling the rate direction of said longitudinalmovement including a lever havinga plurality of positions in each direction of movement thereof, andmeans for causing a diierent speed for each position.

In a grinding machine, a wheel support, a `work support, a hydraulic motor for effecting a vrelative longitudinal movement of said supports,

:speed control means for causing said longituvdinal movement to take place thru a relatively high. speed range, speed control means for effecting said longitudinal movementv thru a relatively Alow speed range, a valve for determining the "direction of said. longitudinal movement, and

means for shifting said valve thru one range to select one speed control means and thru another .rangetovselect another speed control means.

3. In a grinding machine, a work support, a grinding wheel support, mechanism for effecting relative transverse and longitudinal movements `between said supports, mechanism for 4vcontrolling the rate and direction of said longitudinal Ymovement including aleverhaving a plurality of positions in each direction ofmovement thereof, `and lmeans responsive to Vmovement 'to one. or another of said positions fordetermining the rate of said longitudinal movement.

Se. In a grinding'machine, a work support, a grinding Wheel support, mechanisms for. effecting lrelative .transverse and longitudinal movements between said supports including a vhydraulic motor, `a yreversing mechanism for directing fluid `under pressure to one side or the other of said motor, and for directing exhaust uid .thru any one of a plurality of passages, each of said vpassages having means for adjusting the rate of flow therethru.

5. In a grinding machine, Ya .work-support, a

.grinding Wheel support, mechanisms for effect- ,ingrelative .transverse and longitudinal movements between said supports, a selector device for rendering Voperative one or both of `saidmoverments, and means responsive `to the fluid under l,pressure for causing said traversing movement v,for resisting operation of said selector while .the

Vwheel support;is in advance position.

6. In a .grinding machine, a work support,

mechanism foreffecting Ya :longitudinal reciprocation of said support, agrinding wheel support,

-rnechanism for effecting a rapid .transverse :po-

sitioning movement of said support, mechanism for effecting a slow transverse feeding. movement Aof said support, means responsive to said longitudinal reciprocation for effecting said feeding movement by predetermined increments, :and a bypass mechanism for bypassing said incremental feed control Vmeans whereby to .provide .a

`plungecut .feed along with said longitudinal reciprocation '7. In a grinding machine, a work support,

mechanism .for effecting a longitudinal recipro- 'cation ofsaid support including a hydraulic motor, ra reversing .mechanism for controlling :said

:longitudinal reciprocating movement, .a grinding '.wheel support, mechanism lfor effecting a slow transverse feeding movement of :said isupport, means controlled by said reversing Vmechanism forrsupplying fluid under pressure yto said feeding mechanism intermittently, ymeans 'for supplying a continuous flow of iiuid under pres- :sure :to said feed mechanism,.a valve controlled :by saidreversing mechanism and operable inone `position ,fto connect said hydraulic motor with .said .reversing mechanism and for connecting :said feed mechanism .with said intermittentzow of fluid, andin another vposition to disconnect vsald hydraulic motor .and said reversingimechanism and to connect `said vfeed mechanism with Asaid continuousflow of fluid underipressure.

18. In a grinding machine, a work support, la ygrindingwheel support, mechanism for causing .a yrelative longitudinal movement between said supports including a motor connected .to said Work support, a reversing mechanism for effect- -ing areciprocating movement of ysaid motor and said work support, means for actuating said re- .versing.mechanism, mechanism for yeffecting a :relative transverse movementbetweensaid sup- Jportsincluding a second motor, means operable in .response to the :means yfor actuating said re- .versing mechanism `for causing incremental movement of said second motor, and means 'for varying the r.mr-gnitude of said increments Lby .varying theirate of movement of the means-for causing same.

9."In .-a grinding machine, a ywork support, `a grinding wheel support, mechanism Yfor caus- 'ing a relative 4longitudinal ymovement between said supports including a hydraulic motor, 'mech- 

